Parkinson's disease is a progressive disease that results from disrupted balance of intracerebral neurotransmitters, and causes symptoms such as tremor, bradykinesia and postural reflex disturbance, finally leading to severe physical disorder. In addition, with respect to patients suffering from Parkinson's disease, tendency of occurrence of emaciation has been problematic, which results from body weight loss, as compared with healthy individuals of the same age. Thus far, causes of the body weight loss in Parkinson's disease patients have not been elucidated; however, it has been recently revealed that the body weight loss significantly results from a reduction in the amount of body fat (see Lorefalt B et al., Mov. Disord., 24, pp. 885-890 (2009)).